C8 T1 Nerve | Damage Symptoms

| Muscle Group | Action | Clinical Finding | |--------------|--------|------------------| | Intrinsic hand muscles (interossei, lumbricals, hypothenar) | Finger abduction/adduction, fine motor control | Claw hand deformity (MCP hyperextension, IP flexion of ring & little fingers); difficulty with cross-fingers, buttoning, or gripping | | Thenar muscles (median nerve contribution from C8) | Thumb opposition, abduction | Weak pinch grip; inability to make an "O" sign | | Long finger flexors (FDP to ring & little finger – ulnar nerve via C8) | Distal interphalangeal joint flexion | Weak grip, especially ring & little finger flexion | | Wrist flexors (partial – FCU ulnar nerve C8) | Ulnar wrist flexion | Radial deviation of wrist on flexion |